1. Field of the Invention
The invention relates in general to lift couplings and, in particular, to quick disconnect lift couplings that mount to loads through dovetail sockets.
2. Description of the Prior Art
It is well recognized that load lifting devices may be coupled to loads through dovetail sockets. See, for example, Silva U.S. Pat. No. 4,304,432, Silva et al. U.S. Pat. No. 4,575,144, and Silva U.S. Pat. No. 6,131,976. In general, a dovetail socket includes a pair of angularly projecting walls that are adapted to securely engage the toes of a lift coupling. Previously proposed expedients had generally required that elements of the load lifting devices be inserted into a dovetail socket and then rotated to engage the mating surfaces of the dovetail socket. Complicated locking expedients were generally provided to hold the load lifting devices assembled to the dovetail socket. Any impairment by, for example, debris or damage, to the rotative capability of the elements potentially rendered the coupling unusable or unsafe. Unless the elements of the load lifting devices are reliably and ruggedly held together in one assembly when the device is being handled, transported and stored, one element is likely to become lost or broken, rendering the device useless. Also, if any assembly is required at the site of usage, or at a general repair facility, there is the potential for misassembly, resulting in a safety hazard. The manufacturing of forgings and castings is relatively inexpensive as compared to the manufacturing of machined parts. The risks of misassembly, lost elements, damaged elements, and the costs of manufacturing all increase with the number of separate parts. Also, as the number of parts increases the ruggedness of the device diminishes. The device under certain circumstances should be easy to disassemble into its constituent elements so that if one part becomes damaged, it can be replaced or repaired without discarding the entire device. The configuration of the device should be such that it can not be misassembled. The configuration also should be such that where the option of disassembly is not desired, substantially permanent assembly can be easily achieved. Engagement and disengagement to a mating dovetail socket should be accomplished without the use of any tools.
These and other difficulties of the prior art have been overcome according to the present invention.